Method for well cleaning



W. J. CRITES METHOD FOR WELL CLEANING Original Filed Jan. 2l, 1937 Fig.4

v I I! x "Hi Illllll u. lll' INVENTOR WILBUR J. Crm-Es ATTORNEY toutedMIETHIOD FOR WELL ClLEl Wilbur .1. Gritos, lesville, lllkla., assignerto Phillips Petroleum Company, a corporation oi Melaware 2 Claims.

This invention relates to improvements in well cleaning.

More specifically the invention relates to a method and apparatus forcleaning out bottom holes in wells operating with pumps.

In oil well pump installations, the present practice is to attach ascreen to and directly below the standing valve assembly which islocated at the bottom of the accumulation chamber of the pump. Thepurpose of this screen is to keep out larger particles of earth debriswhich might clog the pump. When there is a cave-in or a gradualaccumulation of earth debris in the bottom hole,

oil cannot flow into the screen and the pump be- ]0 comes inoperative.It is then necessary to clean out the bottom hole either by removal ofthe tubing, pump, and screen and subsequent hailing or by backwashingthrough the screen perforations. Since removal of the tubing, pump, andscreen is an expensive operation, the preferred method is backwashing.In the present invention instead of attempting merely to clean out theperforations in the screen as previously done, a suicient quantity ofwater or other suitable liquid is forced into the bottom hole to dilutethe debris therein to a ovving consistency which when admitted tothe-accumulation chamber through the standing valve will be furtherdiluted by liquid retained there for that purpose to a consistencyproduceable by the pump.

The method and apparatus of this invention are readily applicable to agas-lift device of the type disclosed by Stephens et al. in Patent2,142,- 482 issued January 3, 1939. This application is a division of mycopending application, Serial No. 121,688, filed January 21, 1937,entitled Method and apparatus for well cleaning. It is to be understoodhowever that the invention is alsoapplicable to any well using a gaslift pump.

An important object of the invention is the provision of a method andapparatus for cleaning out the bottom hole in a well in an efficientmanner.

A further object of the invention is the provision of a cleanout devicefor the bottom hole of a well which will not interfere with normalpumping operations.

A still further object of the invention is the provision of a cleanoutdevice for the bottom hole of a Well which forms part of the pumpassembly.

Other objects and advantages of the invention will become apparentduring the course of the following description. In the accompanyingdrawing, forming a part of this specification, and in which likenumerals designate like parts throughout the same,

Fig. 1 is a view partly in elevation and partly in section of a deviceembodying the invention,

Fig. 2 is a cross-sectional view taken on the 5 line 2-2 of Fig. 1,

Fig. 3 is a cross-sectional view taken on the line 3-3 of Fig; 1 and inwhich the valve springs have been omitted to simplify the showing,

Fig. 4 is a schematic showing of the device of 10 Fig. 1 in position ina bottom hole, and l Fig. 5 is a view in longitudinal section of anothermbodiment of the lower section of the fitting.

In the drawing, wherein for the purposes of 15 illustration, is show'n apreferred embodiment of my invention, the numeral 6 designates generallya fitting formed for purposes of manufacture by an upper section 'I anda lower section 8. The sections meet at a ground joint 9 and are held 20together by cap screws Il) in recesses I I. Upper section 1 isinternally screw threaded at I2 and lower section 8 has an annular boreI3, screw threaded on both its cylindrical walls at I4 and I5. Engagingthreads I4 is a tube I6 terminating 25 at its lower end in a standingvalve I1 including valve seat I8 and a supporting element I9. Engagingthreads I5 is a tubing 20 spaced from tubing I6 and terminating in abull plug 2| having openings 22 forming a screen. Fitting 6 has pas- 30sages 23 drilled through its side wall near the top closed by plugs 24.Each passage connects through a. port 25 with a bore 26 extendingdownwardly through the wall to a point adjacent the upper end of annularbore I3 with which it is in 35 communication by a port 21. In each bore26 is a valve 28 closing port 25 by the action of a spring 29. Valve 28is spaced from the walls of bore 26 by guides 30.

Fig. 4 shows the arrangement of the device in 40 operating position. Acasing is shown at 3l cemented at 32 to the bore hole wall in theneighborhood of the producing formation. A tubing string 33 is connectedat its lower end to a gaslift pump 34 having a discharge tube 35 and a45 fluid pressure conduit 36 extending from its lower end. Dischargetube 35 extends upwardly through the pump to be connected to a ow string3l which in turn continues upwardly to the surface of the ground. Thespace 38 between strings 50 33 and 31 is hermetically sealed above theground and constitutes a uid pressure conduit to the gas-lift pump 34from a uid pressure pipe 39 at the surface. Pipe 39 includes anintermitter 4I) and a control 'valve 4I. It is apparent from an 55`inspection of Fig. 4 that the device of the present inventionconstitutes a modified accumulation chamber for the gas-lift pumpextending into bottom hole 42. A tube 43 depends from the lower end ofpump 34 and is screw threaded into threads I2 of the fitting 6. Thustube 43, tting 6, tubes I6 and 20 with valve `I1 and bull plug 2| forman accumulation chamber for pump 34 in which the lower part is formed ofconcentric, spaced receptacles, the inner one closed at the bottom bystanding valve I1 and the outer one by bull plug 2I and the space inbetween these receptacles communicating with the interior of theaccumulation chamber at fitting 6 when valves 28 are open.

In Fig. 5 a modification of fitting section 1 of Fig. 1 is shown whereininstead of being integral throughout, the section is shown formed of twotelescoping machined cylinders 1-A and 1-B which may be a more desirableconstruction for purposes of manufacture. In this form threads I4' andl5' are cut in cylinders 1-A and 1-B respectively before they areassembled and to such a depth that on assembly an annular recess I3' isformed. A lip 'I-C is formed on cylinder 1-A to positively position thetwo cylinders with respect to one another.

As is well known to those skilled in the art, the gas-lift pump appliesgas under pressure to the surface of the oil in the accumulation chamberforcing the oil up discharge tube 35 and flow string 31. Springs 29 areso designed that valves 28 are not opened by the usual operatingpressures in the accumulation chamber. When the oil level in theaccumulation chamber has been lowered to a pointnear the lower end ofdischarge tube 35, the gas pressure supplied to pump 34 through fluidconduit 31 is cut 01T by intermitter 40 and the pump operates to exhaustthe gas under pressure from the accumulation chamber, allowing the oilin the bottom hole to ow into the accumulation chamber, filling it againfor a succeeding pressure stage, initiated by the action of theintermitter in reinstating the gas pressure. However, when rock and dirtdebris accumulates in the bottom hole, either from naturaldisintegration of its walls or from a cavein thereof, the openings 22 inbull plug 2| become stopped preventing the oil in the bottom hole fromflowing into the accumulation chamber. The operation of the pump mustthen be stopped and the bottom hole cleaned out. Control valve 4I isclosed cutting off the gas pressure from space 38. Water or othersuitable fluid is admitted to space 38 in suiicient quantity to coverport 23 in the accumulation chamber by the amount of liquid desired tobe forced into the bottom hole as herein later more specificallydescribed. Gas at a pressure higher than the usual pumping pressures isthen applied to space 38, the same pressure being applied to ow string31. The latter step prevents the pump from operating. It can readily beseen that all the liquid above passage 23 will be forced past valve 28,down through the conduit formed by bores 26 and the annular spacebetween the inner and outer receptacles, to the openings in the bullplug and into the bottom hole 42. theapplication of' high 'pressure gascan be continued to agitate the mixture of mud in the bottom hole. Uponrelieving the pressure on space 38 and flow string 31, the gas in theaccumulation chamber above port 23 will be exhausted by the operation ofthe pump. The mud produced outside the bull plug will flow into the bullplug and up through the standing valve where it will be further dilutedby the liquid remaining in the accumulation chamber below passage 23,thus reducing its consistency to a point at which it can be more easilyhandled by the gas-lift pump. The amount of liquid required will differwith the amount and character of the material blocking flow of oil inthe bottom hole. It should be a sulcient quantity to achieve the degreeof consistency of mud in the accumulation chamber mentioned above. Itmay be necessary to repeat the entire'operation several times to restorefull flow of the oil.

It is to be understood that the form of my invention, herewith shown anddescribed, is to be taken as a preferred example of the same, and thatvarious changes in the shape, size, and arrangements of parts may beresorted to without departing from the spirit of my invention, or thescope of the appended claims.

I claim:

l. The method of cleaning out bottom holes in wells which are stopped byearth debris, wherein an accumulation chamber for a pump terminates insaid bottom hole, comprising the steps of admitting liquid underpressure into said bottom hole in quantity suicient to form a owablemixture of said debris and said liquid, while retaining a quantity ofliquid in said accumulation chamber, releasing said pressure wherebysaid mixture flows into said accumulation chamber, said liquid in saidaccumulationvchamber diluting said mixture to a consistency whereby saidmixture can be pumped.

2. The method of cleaning out bottom holes in wells which are stopped byearth debris, wherein an accumulation chamber for a pump terminates insaid bottom hole, comprising the steps of admitting liquid underpressure into said bottom hole in quantity sufficient to form a flow,-able mixture of said debris and said liquid, while retaining a quantityof liquid in said accumulation chamber, agitating said mixture,releasing said pressure whereby said mixture flows into saidaccumulation chamber, said liquid in said accumulation chamber dilutingsaid mixture to a consistency whereby said mixture can be pumped.

WILBUR J. CRITES.

If desirable as in the case of cave-ins

